Surgical management of autogenous bone block graft exposure followed by prosthetic rehabilitation of thin residual ridge

Abstract

Autogenous bone block graft is the gold standard technique for alveolar bone augmentation. However, it is technique sensitive and associated with several complications. Exposure of block graft can affect the outcome of surgery and is challenging to manage. A patient diagnosed with Seibert Class III residual alveolar ridge was managed with autogenous bone block graft. Two dental implants were placed after obtaining sufficient ridge augmentation. The patient presented with exposure of bone block graft after implant placement. A full-thickness mucoperiosteal flap was elevated. Exposed bone was shaved and contoured using piezosurgery. A connective tissue graft with epithelial striation from palate was employed to cover the exposed graft and augment the keratinized tissue. Treatment resulted in complete coverage of block graft and gain in keratinized mucosal dimensions. Prosthetic rehabilitation using screw-retained 3 Unit Bridge was delivered. The results are sustained after 2 years, and the patient is being followed up.

INTRODUCTION

Surgical management of severely compromised alveolar ridge is complex as it requires substantial hard and soft tissue augmentation both vertically and horizontally. Autogenous bone block graft is the gold standard technique for Seibert Class III type alveolar ridge defect. Several systematic reviews on alveolar ridge augmentation suggest predictable improvement in bone quantity and quality with long-term successful implant-supported restorations in those augmented sites.[1,2] However, it is associated with increased morbidity and other complications associated with the specific donor sites. Flap management is crucial in autogenous bone block grafting as the exposure of graft can lead to undue complications and even graft failure. The uses of piezosurgery to harvest and manipulate autogenous bone block grafts have been well described. Piezosurgery creates precise osteotomy with less soft tissue trauma, better healing outcomes, and less noise and vibrations in contrast to conventional surgical burs and saws. Width of keratinized mucosa around implants is critical as its absence can lead to deleterious outcomes, including higher plaque accumulation, gingival inflammation, bleeding on probing, mucosal recession, and even peri-implant bone loss. Connective tissue grafting has been reported with better esthetic outcomes and greater gain in keratinized tissue dimensions.[3]

CASE REPORT

A 23-year-old male patient presented to the outpatient department in June 2018 for the replacement of lower anterior teeth lost due to an accident. He was otherwise fit and well. Clinical examination revealed missing of teeth 41, 42, and 43 and a subsequent vertical and horizontal alveolar ridge deficiency (Seibert Class III). Since the patient was young and wanted fixed teeth utilizing implants, ridge augmentation with autogenous bone block graft was planned and the patient signed informed consent.

Under local anesthesia, a full-thickness mucoperiosteal flap was elevated on the labial aspect of lower canine to canine region with releasing incisions on both sides. Recipient site was decorticated using piezosurgery inserts. Size of the bone block graft was determined using a stent, and the same was harvested from the symphyseal region a little below the recipient site using piezosurgery. Extension of the flap a little deeper was sufficient for exposing the donor site. The graft was secured using a single stabilizing screw. Autogenous bone chips mixed with deproteinized bovine bone was used to fill the margins of the block graft. A collagen membrane covered the graft over which the flap was repositioned and primary closure was obtained. Postoperative healing was uneventful. The bone block graft was well integrated and provided more than sufficient bone in the prospective implant site after 6 months. The patient has consented for implant placement at 41–43. Two GMI implants of size 3.75 mm × 15 mm and 3.3 mm × 15 mm were placed at 43 and 41 sites, respectively, and healing abutments were placed. The implants were in a prosthetically driven position with buccal bone width of 2 mm near the cervical implant collar. Postoperative healing was uneventful. The patient reported for follow-ups till the first 2 months after implant placement. As he moved out for job prospects didn't report for some time. Then after 7 months, he presented with a soft tissue dehiscence on the buccal aspect of the operated site and exposure of some part of bone block graft. On assessment, no evidence for soft tissue dehiscence was found except for a history of mechanical trauma on the treated site during the healing phase [Figure 1]. Implants were stable and well osseointegrated.

Figure 1.

Flap dehiscence with exposure of block graft labial to the clinically stable implants

Shaving off of exposed bone was planned followed by soft tissue augmentation using connective tissue graft with epithelial striation (CTG-ES) from palate. A temporary acrylic removable palatal stent was constructed to wear during the early healing period. After thorough scaling and polishing, the patient was instructed to rinse with a 0.12% chlorhexidine mouthwash and oral hygiene instructions were given. Local anesthesia (2% lignocaine) was administered.

A small trapezoidal full-thickness flap was raised utilizing a horizontal incision at the level of bone exposure and two vertical releasing incisions on either side crossing the mucogingival junction using a no. 15C scalpel [Figure 2]. Flap was reflected not only to remove the necrotic bone but also to facilitate soft tissue grafting to enhance the thickness and width of keratinized tissue. The exposed and slightly yellowish portion of the bone block graft was carefully removed using piezosurgery inserts leaving smooth healthy bone margins [Figures 3 and 4]. The elevated flap was found to be insufficient to cover the block graft, and tension-free primary closure was not possible even after scoring of periosteum. The soft tissue deficit was measured using a stent, and CTG-ES of required dimension was harvested from palate.

Figure 2.

Full-thickness mucoperiosteal flap raised with 2 vertical and 1 horizontal incisions

Figure 3.

The exposed and slightly yellowish portion of the bone block graft was carefully removed using piezosurgery inserts

Figure 4.

After removing exposed portions of bone

CTG-ES was carefully dissected with no. 15C surgical blade from the first molar–premolar regions [Figure 5]. A prefabricated palatal acrylic stent was applied to protect the underlying donor site. The connective tissue portion of CTG-ES was sutured and stabilized to the inner aspect of recipient mucoperiosteal flap using 4-0 absorbable (vicryl) sutures [Figure 6]. The ES portion of CTG-ES covered the dehiscence. The augmented mucoperiosteal flap was advanced to cover the bone entirely and resulted in tensionless primary closure. Flap margins were sutured around the healing abutments with 4-0 absorbable (vicryl) sutures [Figure 7]. Postoperative instructions were given. Amoxicillin 500 mg 8^th hourly daily for 5 days, 0.12% chlorhexidine mouth rinse twice daily for 2 weeks, and ibuprofen (600 mg) 3–4 tablets/day for pain relief were prescribed.

Figure 5.

Subepithelial connective tissue graft with epithelial striation

Figure 6.

Connective tissue graft sutured to the flap margin

Figure 7.

Primary closure obtained after suturing the connective tissue graft with epithelial striation

Healing was uneventful in the immediate postoperative period. The sutures were removed after 2 weeks. The CTG-ES covered the bone exposure and ensured adequate soft tissue thickness and width. Complete closure of exposed autogenous bone block was achieved. The patient was followed up regularly every 2 weeks for the first 3 months. Sufficient soft tissue volume was achieved over a period of 3 months; hence, prosthetic rehabilitation was initiated.

Open tray implant impression was taken using addition silicone. Screw-retained splinted metal ceramic crowns were inserted to replace 41, 42, and 43 [Figures 8-13]. The patient was esthetically and functionally satisfied. He is being followed up regularly for the past 2 years [Figures 14 and 15].

Figure 8.

Mature soft tissue healing at 3 months postoperatively showing adequate keratinized tissue dimensions and complete coverage of exposed bone block graft

Figure 13.

Screw-retained splinted implant prosthesis post-fixation

Figure 14.

Two-year follow-up clinical photograph showing good soft tissue health

Figure 15.

Two-year follow-up IOPAR showing stable crestal bone around implants

Figure 9.

Healed peri-implant mucosae ready for prosthetic phase

Figure 10.

Open tray impression using addition silicone

Figure 11.

Screw-retained implant prosthesis in relation to 41–43 region

Figure 12.

Screw holes of the prosthesis sealed

Healthy peri-implant soft tissue margins are being maintained since the placement of prosthesis with regular use of water irrigators and interproximal brushes. The patient is being followed up on a 3-monthly basis. The plaque control has been satisfactory so far, and the peri-implant soft tissues and crestal bone levels are being maintained in a healthy condition.

DISCUSSION

Lack of proper bone quantity and quality is the major challenge in implant dentistry. Autogenous bone block graft, nevertheless being the gold standard for guided bone regeneration, is highly technique sensitive and associated with numerous postoperative complications, of which flap dehiscence followed by oral exposure of graft is very common and has a detrimental impact on final esthetic outcome of implants in the anterior zone.[4] Soft tissue dehiscence can result in graft exposure, wound infection, and even loss of graft. Flap dehiscence can be due to thin biotype, improper primary closure of flap margins, and suture with tension and systemic factors, although in this particular case, such factors were not involved. It is reported that addition of xenogeneic graft particles and/or collagen membranes could increase the frequency of soft tissue dehiscence.[5] There is absence of consensus regarding therapeutic choice for surgical coverage of exposed block bone graft that supports an osseointegrated dental implant.[4] Surgical correction of soft tissue dehiscence and management of exposed bone block graft supporting a dental implant are cumbersome due to the peculiarities of peri-implant mucosa compared to gingiva around a natural tooth. CTG is the gold standard for peri-implant soft tissue augmentation,[6] hence the technique of choice for such cases. CTG effectively increases soft tissue thickness and width of keratinized gingiva and restores esthetics.[7] In this case, since the wide graft exposure required to be covered, a CTG-ES was employed. CTG-ES is a hybrid soft tissue graft that combines the properties of both free epithelial and CTGs. ES is positioned coronal to the flap margin while the connective tissue portion was covered by the full-thickness flap. It provides better position and stability and augments healing process.[8] Recently, a subperiosteal peri-implant-augmented layer technique has been reported for coverage of minor peri-implant bone dehiscence.[9] In the present case, the area of exposure was relatively large, and the underlying bone was a block graft undergoing integration with the recipient site making employment of such techniques difficult.

Sufficient volume and thickness of the keratinized tissue were obtained with soft tissue grafting, as reported by Rojo et al.[10] Roccuzzo et al.[11] reported that resultant soft tissue bulk around implants obtained with augmentation is sustainable over the long term. Strict patient compliance to postsurgical care and meticulous adherence to personalized standard penetration test visits are essential for the long-term success of soft tissue augmentation procedures around functional implants.[12]

The exposure of a healing bone block graft that supports an integrating dental implant is a difficult clinical situation the successful management of which requires critical thinking, evidence to support clinical decision-making, and good surgical skills. Timely management with meticulous presurgical planning, careful flap management, and rigorous patient follow- up resulted in favorable esthetic and functional results that are maintainable over the long term.

Declaration of patient consent

The authors certify that they have obtained all appropriate patient consent forms. In the form, the patient(s) has/have given his/her/their consent for his/her/their images and other clinical information to be reported in the journal. The patients understand that their names and initials will not be published and due efforts will be made to conceal their identity, but anonymity cannot be guaranteed.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.